1. Field of the Invention
The present invention relates to a method of manufacturing a liquid ejection head and also to a method of processing a substrate.
2. Description of the Related Art
Silicon substrates are typically employed for ink jet printing type liquid ejection heads and a plurality of heating resistors are arranged in rows on the substrate along with a heat storage layer and an electrically insulating layer provided so as to be common to the heating resistors.
Known configurations of liquid ejection head include the one disclosed in U.S. Pat. No. 6,273,557. The liquid ejection head disclosed in U.S. Pat. No. 6,273,557 includes minute ejection ports for ejecting liquid droplets, a flow channel communicating with the ejection ports and an ejection energy generating section provided at a part of the flow channel, which are arranged on a substrate. Additionally, a liquid supply port that communicates with the flow channel is formed on the silicon substrate.
U.S. Pat. No. 6,534,247 describes a method of forming such a liquid supply port by subjecting a silicon substrate to a two-step etching process. (See Specification and FIGS. 5 and 6 of U.S. Pat. No. 6,534,247). With the method described in the above patent document, a liquid supply port is formed by subjecting a substrate to the first etching step that is a crystal anisotropic etching step and then to the second etching step that is a dry etching (reactive ion etching).